1. Field of the Invention
The present invention relates to radiographic pictures, commonly referred to as "X-rays. " More particularly, the present invention relates to an apparatus for making radiographic pictures of objects submerged in an underwater environment.
2. Prior Art
Undersea exploration and industry have created extensive constructions on our ocean floors. This is particularly true in the oil and gas industry where thousands of miles of various sizes and types of piplelines have been laid for the transmission of petroleum products. Additionally, massive drilling and production facilities, called "oil platforms" or "oil rigs" have been constructed, often many miles offshore in deep water. These platforms derive their support and strength from complex foundations, having multiple structural parts and members, called "jackets, " which are anchored to the ocean floor with piling or the like.
While these examples of undersea constructions may be well designed and constructed initially, they are subsequently subjected to abusive forces, such as salt water corrosion, chemical attack, and swift underwater currents. Intense weather conditions such as hurricanes periodically occur which can destroy equipment, particularly that which is not properly maintained. Therefore, a great need exists for a device which can quickly and effectively examine underwater objects in place such as pipelines, oil rig jackets, drilling platforms, piling and the like to deterime their structural integrity. Visual inspection is ineffective where structural parts, or welds may have fractures which are too small, subsurface of coated with marine growth.
Radiography, because of its ability to make photographs of solid material density, has been extensively used in examination of several types of structural members and like objects. Radiography is well suited for examining structures such as pipelines, welds, piling or girders. While radiographs are well suited and extensively used to examine solid structureal members, there is a need for an economical, simple, and effective apparatus for making radiographic pictures in an underwater environment.
Two prior art devices for underwater radiography are disclosed in U.S. Pat. No. 3,891,845, issued June 24, 1975 to Paul N. English; and U.S. Pat. No. 3,673,407, issued June 27, 1972 to George C. Wiswell.
Generall, the prior art devices have failed to solve the problem of underwater radiography staisfactorily. Prior art devices are generally complex and awkward to handle. Since underwater radiography devices are generally handled and operated by a diver, there is a need for ease of operation and ease of transportation. Radiography demands that water be void from the area traversed by the radiation beam and that there be no significant backscattering caused by the water. The presence of water in the beam transmission are distorts the radiographic pictures by causing attenuation of the radiation beam. An additional problem in underwater radiography is orientation of the radiation beam, the object to be radiographed, and the sensitized film from which are produced the final radiographies. Some prior art devices require that the diver position and orient the film and radiation beam around the object while underwater. This method is time consuming and therefore costly. It also requires additional skill and training in the diver.
3. General Discussion of the Present Invention
The device of the present invention solves these prior art problems by providing a watertight, self contained, fully equipped and oriented underwater radiography device.
It is an object of the present invention to provide an apparatus for underwater radiography which enables the user to quickly and efficiently take underwater radiographs of desired objects. It is a further object of the present invention to provide a device for making underwater radiographs without requiring extensive operation by the user to remove water from the radiation beam transmission area. It is still a further object to insure that no significant backscattering occur due to the presence of water in proximity to the backside of the radiographic source.